Portable golf swing practice devices are generally used indoors during winter to exercise a golfer's skills in swinging a golf club with precision. These devices have been in use for many years, and perhaps the most common ones are characterised by their structures, each having a floor pad on which is mounted a golf ball. The ball is held to the floor pad by an elastic cord, or by other tee structure mounted on a slider that is connected to a spring. When the ball is struck, the elastic cord or the spring extends and causes a pointer to record the ball's travel distance. The extension of the spring or of the cord is then converted in yards of theoretical distance the ball could have travelled on a normal golf course. Examples of these golf swing practice devices are described in the following documents;    U.S. Pat. No. 3,830,504 issued to B. B. Koo on Aug. 20, 1974;    U.S. Pat. No. 4,084,822 issued to J. H. Keeton on Apr. 18, 1978;    U.S. Pat. No. 4,609,197 issued to G. M. Vodin on Sep. 2, 1986;    U.S. Pat. No. 5,417,427 issued to M. S. Doane on May 23, 1995.
In another type of similar portable golf practice devices, the elastic cord extends and causes the ball to hit one of several targets on the floor pad so as to leave a mark on the target or to trigger a signal from one or more switches incorporated in the floor pad. The mark on the target or the triggered signal is representative of the theoretical ball direction, velocity or range. Examples of golf practice devices of this other type are described in the following documents:    U.S. Pat. No. 2,656,720 issued to F. W. Sonnett on Oct. 27, 1953;    U.S. Pat. No. 5,386,997 issued to G. C. Smith on Feb. 7, 1995.
Although several portable golf swing practice devices can be found in the prior art, those that are of a particular interest herein are those where the balls are held to the floor pads by means of elastic tether cords. It has been found that these tether cords are particularly vulnerable to shear stresses and cuts. The occurrence of these stresses is particularly noticeable when the ball is struck low. The cords on these devices must be replaced often, or else, the risk of a cord breakage remains high. Therefore, it is believed that there is a market need for a golf swing practice device that has an effective cord shield thereon to minimize transverse shocks on the cord and so that the device can be used safely indoors.